body
{
    margin: 0;
    padding: 0;
    background: #000000;
}
a
{
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%,-50%);
width: 200px;
height: 60px;
text-align: center;
line-height: 60px;
color: #ffffff;
font-size: 24px;
text-transform: uppercase;
text-decoration: none;
font-family: sans-serif;
box-sizing: border-box;
background: linear-gradient(90deg,#03a9f4,#f441a5,#ffeb3b,#03a9f4);
background-size: 400%;
border-radius: 30px;
z-index: 1;
}
a:hover
{
    animation: animate 8s linear infinite;
}
@keyframes animate
{
    0%
    {
        background-position: 0%;
    }
   100%
    {
        background-position:400%;
    }
}
a:before
{
content: "";
position: absolute;
top: -5px;
left: -5px;
right: -5px;
bottom: -5px;
z-index: -1;
background: linear-gradient(90deg,#03a9f4,#f441a5,#ffeb3b,#03a9f4);
background-size: 400%;
border-radius: 40px;
opacity: 0;
transition: 0.2ms;
}
a:hover:before
{
    filter: blur(20px);
    opacity: 1;
    animation: animate 8s linear infinite;
}

